Which statement is true regarding aircrew duties and eyewear?

The statement that only Air Force provided spectacles and sunglasses are to be used is accurate because it reflects the stringent regulations and standards set for aircrew personnel. Ensuring a uniformity in eyewear maintains a high level of safety and performance within aviation operations. The prescribed eyewear is designed to meet specific optical standards that are essential for flying, which includes protection from glare and other environmental factors that can affect visibility and overall performance in the cockpit.

Using non-standard or personal eyewear could result in inadequate vision correction or protection, which might compromise safety in a critical aviation environment. Therefore, the emphasis on using only Air Force provided spectacles and sunglasses aligns with best practices in aviation safety and operational readiness.